using UnityEngine.Graphing;

namespace UnityEngine.MaterialGraph
{
    [Title("Math/Color/Hue")]
    public class HueNode : Function1Input, IGeneratesFunction
    {
        public HueNode()
        {
            name = "Hue";
        }

        protected override string GetFunctionName()
        {
            return "unity_hue_" + precision;
        }

        protected override MaterialSlot GetInputSlot()
        {
            return new MaterialSlot(InputSlotId, GetInputSlotName(), kInputSlotShaderName, SlotType.Input, SlotValueType.Vector1, Vector4.zero);
        }

        protected override MaterialSlot GetOutputSlot()
        {
            return new MaterialSlot(OutputSlotId, GetOutputSlotName(), kOutputSlotShaderName, SlotType.Output, SlotValueType.Vector3, Vector4.zero);
        }

        //TODO:Externalize
        //Reference code from:https://github.com/Unity-Technologies/PostProcessing/blob/master/PostProcessing/Resources/Shaders/ColorGrading.cginc#L175
        public void GenerateNodeFunction(ShaderGenerator visitor, GenerationMode generationMode)
        {
            var outputString = new ShaderGenerator();
            outputString.AddShaderChunk(GetFunctionPrototype("arg1"), false);
            outputString.AddShaderChunk("{", false);
            outputString.Indent();
            outputString.AddShaderChunk(precision + "4 K = " + precision + "4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);", false);
            outputString.AddShaderChunk(precision + "3 P = abs(frac(arg1.xxx + K.xyz) * 6.0 - K.www);", false);
            outputString.AddShaderChunk("return 1 * lerp(K.xxx, saturate(P - K.xxx), 1);", false);
            outputString.Deindent();
            outputString.AddShaderChunk("}", false);

            visitor.AddShaderChunk(outputString.GetShaderString(0), true);
        }
    }
}